Pine shaped metal nano-scaled grating

ABSTRACT

A pine shaped metal nano-scaled grating, the grating including a substrate and a plurality of three-dimensional nanostructures located on the substrate, wherein each three-dimensional nanostructure comprises a first rectangular structure, a second rectangular structure, and a triangular prism structure; the first rectangular structure is located on the substrate, the second rectangular structure is located on the first rectangular structure, the triangular prism structure is located on the second rectangular structure, a first width of a bottom surface of the triangular prism structure is equal to a second width of a first top surface of the second rectangular structure and greater than a third width of a second top surface of the first rectangular structure, and the first rectangular structure comprises a first metal and the triangular prism structure comprises a second metal.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims all benefits accruing under 35 U.S.C. § 119 fromChina Patent Application No. 201710288829.X, filed on Apr. 27, 2017, inthe China Intellectual Property Office, the disclosure of which isincorporated herein by reference.

FIELD

The subject matter herein generally relates to a pine shaped metalnano-scaled grating.

BACKGROUND

Metal nanostructures play an important role in many fields, such asnano-optics, biochemical sensor, precision optical instruments withultra-high resolution imaging, surface plasma, and surface plasmalithography. In the prior art, metal nanostructures can be made bylift-off process, milling process of focused ion beam, orelectrochemistry method. However, since the above methods can introducechemical reagents, it is difficult to achieve a nanostructure having aspecific morphology. So it is a challenges to make a metal nanostructurehaving a specific morphology.

In the processing of nanostructures, the rate of chemical corrosiondepends on the chemical properties of materials. For example, sincedifferent crystal orientations of silicon have different corrosionrates, a specific silicon three-dimensional nanostructure can beobtained. However, it is difficult to obtain specific three-dimensionalnanostructures for most metal crystals by chemical corrosion. Dryetching methods include reaction ion etching (RIE) method andinductively coupled plasma etching method. The rate of dry etchingdepends on the reaction surface of ions. The etching rate of thereaction surface is greater than the etching rate of the other surfaces.A specific nanostructure can be obtained by reasonable etching rateratios. The focused ion beam induced etching (FIBIE) method is also oneof the dry etching methods for preparing three-dimensionalnanostructures. However, only inclined trough structures can be obtainedby the FIBIE method, and the sizes of the inclined trough structures aretoo large and it is difficult to obtain etching masks. Furthermore, itis particularly difficult to obtain three-dimensional goldnanostructures.

What is needed, therefore, is to provide a pine shaped metal nano-scaledgrating for solving the problem discussed above.

BRIEF DESCRIPTION OF THE DRAWINGS

Many aspects of the embodiments can be better understood with referencesto the following drawings. The components in the drawings are notnecessarily drawn to scale, the emphasis instead being placed uponclearly illustrating the principles of the embodiments. Moreover, in thedrawings, like reference numerals designate corresponding partsthroughout the several views. Implementations of the present technologywill now be described, by way of example only, with reference to theattached figures, wherein:

FIG. 1 is a structural schematic view of one embodiment of a pine shapedmetal nano-scaled grating.

FIG. 2 is a sectional view of the pine shaped metal nano-scaled gratingof FIG. 1.

FIG. 3 is a structural schematic view of one embodiment of a pine shapedmetal nano-scaled grating forming different patterns.

FIG. 4 is an exploded view of one embodiment of the three-dimensionalnanostructures.

FIG. 5 is a flow chart of one embodiment of a method for making the pineshaped metal nano-scaled grating.

FIG. 6 is a flow chart of one embodiment of a method for making apatterned first mask layer.

FIG. 7 is a low magnification Scanning Electron Microscope (SEM) imageof the pine shaped metal nano-scaled grating.

FIG. 8 is a high magnification SEM image of the pine shaped metalnano-scaled grating.

FIG. 9 is a flow chart of one embodiment of a method for making the pineshaped metal nano-scaled grating.

FIG. 10 is a structural schematic view of one embodiment of a pineshaped metal nano-scaled grating.

FIG. 11 is a structural schematic view of one embodiment of a pineshaped metal nano-scaled grating.

FIG. 12 is a flow chart of one embodiment of a method for making thepine shaped metal nano-scaled grating.

DETAILED DESCRIPTION

It will be appreciated that for simplicity and clarity of illustration,where appropriate, reference numerals have been repeated among thedifferent figures to indicate corresponding or analogous elements. Inaddition, numerous specific details are set forth in order to provide athorough understanding of the embodiments described herein. However, itwill be understood by those of ordinary skill in the art that theembodiments described herein can be practiced without these specificdetails. In other instances, methods, procedures, and components havenot been described in detail so as not to obscure the related relevantfeature being described. The drawings are not necessarily to scale, andthe proportions of certain parts may be exaggerated to better illustratedetails and features. The description is not to be considered aslimiting the scope of the embodiments described herein.

Several definitions that apply throughout this invention will now bepresented.

The connection can be such that the objects are permanently connected orreleasably connected. The term “substantially” is defined to beessentially conforming to the particular dimension, shape or other wordthat substantially modifies, such that the component need not be exact.The term “comprising” means “including, but not necessarily limited to”;it specifically indicates open-ended inclusion or membership in aso-described combination, group, series and the like. It should be notedthat references to “an” or “one” embodiment in this disclosure are notnecessarily to the same embodiment, and such references mean at leastone.

Referring to FIG. 1 and FIG. 2, an embodiment of a pine shaped metalnano-scaled grating 10 comprises a substrate 100 and a plurality ofthree-dimensional nanostructures 110 located on a surface of thesubstrate 100. The plurality of three-dimensional nanostructures 110 arepine shaped structures.

The substrate 100 can be an insulating substrate or a semiconductorsubstrate. The material of the substrate 100 can be silicon, silicondioxide, silicon nitride, quartz, glass, gallium nitride, galliumarsenide, sapphire, alumina, or magnesia. The size, thickness and shapeof the substrate 100 can be selected according to need. In oneembodiment, the material of the substrate 100 is quartz.

The plurality of three-dimensional nanostructures 110 can be arrangedside by side and extend along a straight line, a fold line, or a curveline. The extending direction is parallel to a first surface 1002 of thesubstrate 100. Referring to FIG. 3, the extending direction can be anydirection which is parallel to the first surface 1002 of the substrate100. The term “side by side” means that two adjacent three-dimensionalnanostructures 110 are substantially parallel with each other along theextending direction. The distance between two adjacent three-dimensionalnanostructures 110 is in a range from 0 nanometer to 200 nanometers. Theplurality of three-dimensional nanostructures 110 can be continuous ordiscontinuous along the extending direction. In one exemplaryembodiment, the plurality of three-dimensional nanostructures 110 arecontinuous, the extending direction of the three-dimensionalnanostructures 110 extends side by side, the three-dimensionalnanostructures are strip-shaped structures, and cross sections of thethree-dimensional nanostructures have the same pine shapes and the samearea.

Referring to FIG. 4, the three-dimensional nanostructures 110 are pineshaped ridges located on the first surface 1002 of the substrate 100.The pine shaped ridges comprise a first rectangular structure 121, asecond rectangular structure 131, and a triangular prism structure 141.The first rectangular structure 121 comprises a first top surface 1212,and the first top surface 1212 is away from the substrate 100. Thesecond rectangular structure 131 is located on the first top surface1212. The second rectangular structure 131 comprises a second topsurface 1312, and the second top surface 1312 is away from the firstrectangular structure 121. The triangular prism structure 141 is locatedon the second top surface 1312. The geometric centers of the firstrectangular structure 121, the second rectangular structure 131 and thetriangular prism structure 141 are on the same axis. The firstrectangular structure 121 and the triangular prism structure 141 areboth metal layers. The second rectangular structure 131 can isolate thefirst rectangular structure 121 and the triangular prism structure 141.

The triangular prism structure 141 comprises a first triangle surface1410 and a second triangle surface 1412 opposite to and substantiallyparallel with the first triangle surface 1410. The sizes and shapes ofthe first triangle surface 1410 and the second triangle surface 1412 areboth the same. The triangular prism structure 141 further comprises afirst rectangular side 1414, a second rectangular side 1416, and a thirdrectangular side 1418 connected to the first triangle surface 1410 andthe second triangle surface 1412. The projection of the first trianglesurface 1410 coincides with the projection of the second trianglesurface 1412. The shapes of the first triangle surface 1410 and thesecond triangle surface 1412 are both isosceles triangle. The thirdrectangular side 1418 is in contact with the second top surface 1312 ofthe second rectangular structure 131. The side surface of the firstrectangular structure 121 is perpendicular to the first surface 1002 ofthe substrate 100. The side surface of the second rectangular structure131 is perpendicular to the first top surface 1212 of the firstrectangular structure 121, thus the side surface of the secondrectangular structure 131 is also perpendicular to the first surface1002 of the substrate 100.

The width d1 of the first rectangular structure 121 is in a range of 5nanometers to 400 nanometers, the height h1 of the first rectangularstructure 121 is in a range of 20 nanometers to 500 nanometers.Furthermore, the width d1 of the first rectangular structure 121 can bein a range of 12 nanometers to 320 nanometers, the height h1 of thefirst rectangular structure 121 can be in a range of 50 nanometers to200 nanometers. In one exemplary embodiment, the width d1 of the firstrectangular structure 121 is 50 nanometers, the height h1 of the firstrectangular structure 121 is 100 nanometers. The width d2 of the secondrectangular structure 131 is in a range of 50 nanometers to 450nanometers, the height h2 of the second rectangular structure 131 is ina range of 5 nanometers to 100 nanometers. Furthermore, the width d2 ofthe second rectangular structure 131 can be in a range of 80 nanometersto 380 nanometers, the height h2 of the second rectangular structure 131can be in a range of 5 nanometers to 60 nanometers. In one exemplaryembodiment, the width d2 of the second rectangular structure 131 is 100nanometers, the height h2 of the second rectangular structure 131 is 10nanometers. The width d3 of the triangular prism structure 141 is in arange of 50 nanometers to 450 nanometers, the height h3 of thetriangular prism structure 141 is in a range of 40 nanometers to 800nanometers. Furthermore, the width d3 of the triangular prism structure141 can be in a range of 80 nanometers to 380 nanometers, the height h3of the triangular prism structure 141 can be in a range of 130nanometers to 400 nanometers. In one exemplary embodiment, the width d3of the triangular prism structure 141 is 100 nanometers, the height h3of the triangular prism structure 141 is 200 nanometers. The width d3 ofthe triangular prism structure 141 is the width of the third rectangularside 1418 of the triangular prism structure 141. The width d3 of thetriangular prism structure 141 is equal to the width d2 of the secondrectangular structure 131. The third rectangular side 1418 of thetriangular prism structure 141 is completely coincident with the secondtop surface 1312 of the second rectangular structure 131. The width d3of the triangular prism structure 141 is greater than the width d1 ofthe first rectangular structure 121.

Referring to FIG. 5, an embodiment of a method of making the pine shapedmetal nano-scaled grating 10 comprises:

-   -   S10, providing a substrate 100;    -   S20, forming a first metal layer 120 on the substrate 100,        forming an isolation layer 130 on the first metal layer 120, and        locating a second metal layer 140 on the isolation layer 130;    -   S30, placing a first mask layer 151 on the second metal layer        140, wherein the first mask layer 151 covers partial surface of        the second metal layer 140, and other surface is exposed;    -   S40, etching the second metal layer 140 to obtain a plurality of        parallel and spaced triangular prism structures 141;    -   S50, etching the isolation layer 130 to obtain a plurality of        parallel and spaced second rectangular structures 131;    -   S60, etching the first metal layer 120 to obtain a plurality of        parallel and spaced first rectangular structures 121; and    -   S70, removing the first mask layer 151 to obtain the pine shaped        metal nano-scaled grating 10.

In step S10, the substrate 100 can be an insulating substrate or asemiconductor substrate which includes a smooth surface. The material ofthe substrate 100 can be glass, quartz, gallium nitride, galliumarsenide, sapphire, alumina, magnesium oxide, silicon, silicon dioxide,or silicon nitride. The size, thickness and shape of the substrate 100can be selected according to need. In one exemplary embodiment, thematerial of the substrate 100 is quartz. The substrate 100 can becleaned by using a standard process. Furthermore, the substrate 100 canbe treated with a hydrophilic treatment.

In step S20, the first metal layer 120 is deposited on the substrate100, and the second metal layer 140 is deposited on the isolation layer130. The method of depositing the first metal layer 120 and the secondmetal layer 140 can be electron beam evaporation method or ionsputtering method. The material of the first metal layer 120 and thesecond metal layer 140 can be metals with surface plasmon polaritons,such as gold, silver, copper, and aluminum. In one exemplary embodiment,the material of the first metal layer 120 and the second metal layer 140is gold. The thickness of the first metal layer 120 is in a range of 20nanometers to 500 nanometers. Furthermore, the thickness of the firstmetal layer 120 can be in a range of 50 nanometers to 200 nanometers. Inone exemplary embodiment, the thickness of the first metal layer 120 is100 nanometers. The thickness of the second metal layer 140 should begreater than 40 nanometers so that the second metal layer 140 can be afree-standing structure after removing the first mask layer 151. Thefree-standing structure is that the second metal layer 140 can keep acertain shape without any supporter. The thickness of the second metallayer 140 can be in a range of 40 nanometers to 800 nanometers.Furthermore, the thickness of the second metal layer 140 can be in arange of 130 nanometers to 400 nanometers. In one exemplary embodiment,the thickness of the second metal layer 140 is 200 nanometers.

The isolation layer 130 is used to isolate the first metal layer 120 andthe second metal layer 140, thus the first metal layer 120 is notdestroyed when the second metal layer 140 is etched. When the materialof the first metal layer 120 is different from the material of thesecond metal layer 140, the isolation layer 130 can be omitted. Thematerial of the isolation layer 130 can be metal or metal oxide, such aschromium, tantalum, tantalum oxide, titanium dioxide, silicon, orsilicon dioxide. The thickness of the isolation layer 130 can be in arange of 5 nanometers to 100 nanometers. Furthermore, the thickness ofthe isolation layer 130 can be in a range of 5 nanometers to 60nanometers. When the material of the isolation layer 130 is metal, thematerial of the isolation layer 130 should be different from thematerial of the first metal layer 120 and the second metal layer 140. Inone exemplary embodiment, the material of the isolation layer 130 ischromium, and the thickness of the isolation layer 130 is 10 nanometers.

In step S30, the first mask layer includes a body 154, and the body 154defines a plurality of fourth openings parallel with and spaced fromeach other. The method for making the first mask layer 151 can beoptical etching method, plasma etching method, electron beam etchingmethod, focused ion beam etching method, hot embossing method, ornanoimprinting method. In one exemplary embodiment, the first mask layer151 is formed on the second metal layer 140 by nanoimprinting method.Compared with other methods, the nanoimprinting method for making thefirst mask layer 151 has a plurality of advantages, such as highprecision, high efficiency, low energy consumption, low temperatureoperation, and low cost.

Referring to FIG. 6, the nanoimprinting method for making the first masklayer 151 on the second metal layer 140 comprises:

-   -   S301, providing a first mask layer preform 150 and a second mask        layer preform 160 in that order on the second metal layer 140;    -   S302, providing a template 170 with nanoscale patterned surface,        bonding the nanoscale patterned surface of the template 170 to        the second mask layer preform 160 at room temperature, then        pressing the template 170 and the second mask layer preform 160;    -   S303, removing the template 170 to transfer the nanoscale        patterns of the template 170 to the surface of the second mask        layer preform 160, wherein a fifth recessed portion 162 and a        fifth convex portion 164 are formed on the surface of the second        mask layer preform 160;    -   S304, removing a part of the second mask layer preform 160 to        form a second mask layer 161 which defines a fifth opening 163,        wherein the part of the second mask layer preform 160        corresponds to the fifth recessed portion 162, and a part of the        first mask layer preform 150 corresponding to the fifth opening        163 is exposed;    -   S305, removing the part of the first mask layer preform 150 that        is exposed;    -   S306, removing the second mask layer 161 to obtain a first mask        layer 151.

In step S301, the material of the first mask layer preform 150 can behomemade photoresist or commercial photoresist, such aspolymethylmethacrylate (PMMA), silicon on glass (SOG), ZEP520, hydrogensilsesquioxane (HSQ), SAL601. In one exemplary embodiment, the materialof the first mask layer preform 150 is ZEP520.

The photoresist can be provided by spin coating or droplet coating. Themethod for making the first mask layer preform 150 comprises followingsteps: firstly, spin coating photoresist on the second metal layer 140,wherein the rotation speed can be in a range of 500 rpm to 6000 rpm, andthe time can be in a range of 0.5 minutes to 1.5 minutes; secondly,baking the photoresist at a temperature of 140 degrees to 180 degreesfor 3 minutes to 5 minutes. The first mask layer preform 150 is formedon the surface of the second metal layer 140. The thickness of the firstmask layer preform 150 can be in a range of 160 nanometers to 380nanometers. In one exemplary embodiment, the thickness of the first masklayer preform 150 is 260 nanometers.

The second mask layer preform 160 can be imprinted at room temperature,also should have good structural stability and high resolution. Forexample, the impression resolution of the second mask layer preform 160can be less than 10 nanometers. The material of the second mask layerpreform 160 can be HSQ, SOG, or other silicone oligomers. The thicknessof the second mask layer preform 160 can be in a range of 80 nanometersto 280 nanometers. Furthermore, the thickness of the second mask layerpreform 160 can be in a range of 100 nanometers to 160 nanometers. Inone exemplary embodiment, the thickness of the second mask layer preform160 is 121 nanometers. Since the second mask layer preform 160 can bemechanically embossed easily, the accuracy of nanoscale patterns formedon the first mask layer preform 150 is high. Thus the accuracy ofetching the second metal layer 140 is improved. In one exemplaryembodiment, the material of the second mask layer preform 160 is HSQ.The state of HSQ is water-soluble vitreous with good mobility at roomtemperature, and become a cross-linked state after dehydration. The HSQcan flow spontaneously into channels of the template under pressure.

The method for making the second mask layer preform 160 comprisesfollowing steps: firstly, spin coating the resist HSQ on the first masklayer preform 150, wherein the rotation speed is in a range of 3000 rpmto 6500 rpm, and the spin-coating time is in a range of 0.6 minutes to1.8 minutes, the spin coating of the HSQ is performed under highpressure; secondly, curing the resist HSQ to form a second mask layerpreform 160.

In step S302, the template 170 can be a positive template or a negativetemplate. In one exemplary embodiment, the template 170 is a negativetemplate. The template 170 includes a plurality of spaced sixth recesses172 and a plurality of sixth convex portions 174 between adjacent sixthrecesses 172. The sixth recesses 172 can be stripe-shaped recesses orlattice-shaped recesses. In one exemplary embodiment, the sixth recesses172 are stripe-shaped recesses, the sixth convex portions 174 arestripe-shaped convex portions, the sixth recesses 172 and the sixthconvex portions 174 are arranged alternately. Furthermore, the sixthrecesses 172 extend along the straight line to the edges of the template170. Each sixth recess and sixth convex portion form an unit. The lengthof the unit can be in a range of 90 nanometers to 1000 nanometers.Furthermore, the length of the unit can be in a range of 121 nanometersto 650 nanometers. The width of the sixth recess 172 can be equal to thewidth of the sixth convex portions 174 or not. The width of the sixthrecess 172 can be in a range of 40 nanometers to 450 nanometers. Thewidth of the sixth convex portions 174 can be in a range of 50nanometers to 450 nanometers. In one exemplary embodiment, the length ofthe unit is 200 nanometers, the width of the sixth recess 172 is 100nanometers. The height of the sixth convex portions 174 can be in arange of 10 nanometers to 1000 nanometers. Furthermore, the height ofthe sixth convex portions 174 can be in a range of 20 nanometers to 800nanometers. Furthermore, the height of the sixth convex portions 174 canbe in a range of 30 nanometers to 700 nanometers. In one exemplaryembodiment, the height of the sixth convex portions 174 is 200nanometers.

The material of the template 170 can be hard materials such as nickel,silicon, or silicon dioxide. The material of the template 170 can alsobe flexible materials such as PET, PMMA, or PS. In one exemplaryembodiment, the material of the template 170 is silicon dioxide.

The surface having nanoscale patterns of the template 170 is bonded tothe second mask layer preform 160 at room temperature. When the template170 is pressed, the degree of vacuum is in a range of 5×10⁻⁴-1.5×10⁻²bar and the applied pressure is in a range of 2 Psi to 100 Psi, and thetime of applying pressure is in a range of 2 minutes to 30 minutes. Inone exemplary embodiment, the degree of vacuum is 10⁻³ bar, the appliedpressure is 25 Psi, the time of applying pressure is 5 minutes.

The sixth convex portions 174 of the template 170 are presses into theinside of the second mask layer preform 160 and the second mask layerpreform 160 is deformed under the pressure to form a preform layerhaving nanoscale patterns. The part of the second mask layer preform 160corresponding to the sixth convex portions 174 is compressed to form thefifth recesses 162. The HSQ flows into the sixth recess 172 of thetemplate 170 under pressure, and the fifth convex portion 164 is formedon the second mask layer preform 160.

In step S303, a plurality of parallel and spaced fifth recesses 162 andfifth convex portions 164 are formed on the preform layer after removingthe template 170. The size and shape of the fifth recesses 162 are thesame as that of the sixth convex portions 174. The size and shape of thefifth convex portions 164 are the same as that of the sixth recesses172. The depth of the fifth recesses 162 is in a range of 100 nanometersto 190 nanometers.

In step S304, the part of the second mask layer preform 160corresponding to the fifth recesses 162 can be removed by plasma etchingmethod. The etching gas can be selected according to the material of thesecond mask layer preform 160. In one exemplary embodiment, the part ofthe second mask layer preform 160 can be removed by fluorocarbon (CF₄)reactive plasma etching to form the second mask layer 161. The power ofthe CF₄ reactive plasma etching is in a range of 10 watts to 150 watts;the volumetric flow rate of the CF₄ plasma is in a range of 2 sccm to100 sccm (standard-state cubic centimeter per minute); the pressure isin a range of 1 Pa to 15 Pa, the etching time is in a range of 2 secondsto 4 minutes. In one exemplary embodiment, the power of the etchingsystem is 40 watts, the volumetric flow rate of the CF₄ plasma is 26sccm, the pressure is 2 Pa, and the etching time is 10 seconds. The partof the second mask layer preform 160 corresponding to the fifth recesses162 are removed by etching to form the fifth openings 163. The part ofthe second mask layer preform 160 corresponding to the fifth convexportions 164 is simultaneously etched and become thinner. The height ofthe fifth convex portions 164 is in a range of 90 nanometers to 180nanometers.

In step S305, the part of the first mask layer preform 150 can beremoved by oxygen gas plasma to form the first mask layer 151. The powerof the oxygen gas plasma system is in a range of 10 watts to 250 watts,the volumetric flow rate of oxygen gas plasma is in a range of 2 sccm to100 sccm, the air pressure is in a range of 0.5 Pa to 50 Pa, the etchingtime is in a range of 5 seconds to 5 minutes. In one exemplaryembodiment, the power of the oxygen gas plasma system is 78 watts, thevolumetric flow rate of oxygen gas plasma is 12 sccm, the air pressureis 26 Pa, the etching time is 30 seconds. After the part of the firstmask layer preform 150 being removed, the first mask layer preform 150defines a fourth opening 153 corresponding to the fifth opening 163. Thesecond metal layer 140 corresponding to the fourth opening 153 isexposed. Since the HSQ is crosslinked under oxygen gas plasma, the fifthconvex portions 164 can allow the first mask layer 151 to have a highresolution.

In step S306, the second mask layer 161 can be removed by solvent. Sincethe second mask layer 161 can be dissolved and the first mask layer 151can not be dissolved by the solvent, when the second mask layer 161 isremoved, the first mask layer is exposed and not removed. In oneexemplary embodiment, the solvent is water. After the second mask layer161 being removed, the body 154 of the first mask layer 151 is exposed,and the body 154 corresponds to the fifth convex portions 164.

In step S40, the structure obtained after the step S30 is placed in areactive plasma system for etching, thus a plurality of parallel andspaced triangular prism structures 141 are obtained, the plurality oftriangular prism structures 141 are arranged. The etching gas in theetching system is a mixed gas of a physical etching gas and a reactiveetching gas. The physical etching gas can be argon gas, or helium, andthe reactive etching gas can be oxygen gas, chlorine, boron trichloride,or tetrachloride carbon. The physical etching gas and the reactiveetching gas can be selected according to the material of the secondmetal layer 140 and the first mask layer 151 so that the etching gas hasa higher etching rate. For example, when the material of the secondmetal layer 140 is gold, platinum, or palladium, the physical etchinggas is argon gas. When the material of the second metal layer 140 iscopper, the physical etching gas is helium. When the material of thesecond metal layer 140 is aluminum, the physical etching gas is argongas. In one exemplary embodiment, the physical etching gas is argon gas,and the reactive etching gas is oxygen gas.

The physical etching gas and the reactive etching gas are introducedinto the etching system. On the one hand, the body 154 of the first masklayer 151 is progressively etched by the reactive etching gas; on theother hand, the exposed second metal layer 140 can also be etched by thephysical etching gas. As the first mask layer 151 is progressivelyetched, the width of the fourth opening 153 gradually becomes greater.Since the exposed part of the second metal layer 140 corresponds to thefourth opening 153, the etching width of the exposed part graduallybecomes greater from bottom to top. The first mask layer 151 can beremoved or partially removed by the reactive etching gas. The exposedpart of the second metal layer 140 can be removed or partially removedby the physical etching gas. The ratio between the horizontal etchingrate and the vertical etching rate can be selected by adjusting therelationship of volumetric flow, pressure and power of argon gas andoxygen gas. The triangular prism structures 141 can be obtained byadjusting the ratio. The second metal layer 140 defines a plurality ofparallel and spaced third openings 143 and comprises a plurality oftriangular prism structures 141. The isolation layer 130 is exposedthrough the third openings 143.

The volume flow rate of the physical etching gas is in a range of 20sccm to 300 sccm. The volume flow rate of the reactive etching gas is ina range of 2 sccm to 20 sccm. The pressure of the etching system is in arange of 16 Pa to 180 Pa, the power of the etching system is in a rangeof 11 watts to 420 watts, and the etching time is in a range of 5seconds to 3 minutes. In one exemplary embodiment, the volumetric flowrate of argon gas is 48 sccm, the volumetric flow rate of oxygen gas is5 sccm, the pressure of the etching system is 26 Pa, the power of theetching system is 70 watts, and the etching time is in a range of 15seconds to 20 seconds.

In step S50, a plurality of parallel and spaced second rectangularstructures 131 can be obtained by etching the isolation layer 130. Inone exemplary embodiment, the material of the isolation layer 130 ischromium, the etching gas is a mixed gas of oxygen gas and chlorine gas.The power of the reactive plasma system can be in a range of 5 watts to210 watts. Furthermore, the power of the reactive plasma system can bein a range of 10 watts to 88 watts. In one exemplary embodiment, thepower of the reactive plasma system is 22 watts. The volume flow rate ofoxygen gas can be in a range of 3 sccm to 35 sccm, the volume flow rateof chlorine gas can be in a range of 6 sccm to 200 sccm. In oneexemplary embodiment, the volume flow rate of oxygen gas is 5 sccm, andthe volume flow rate of chlorine gas is 26 sccm, the air pressure is ina range of 8 Pa to 150 Pa, the pressure of the system is 26 Pa. Theetching time is in a range of 5 seconds to 1 minutes. In one exemplaryembodiment, the etching time is 15 seconds.

The isolation layer 130 defines a plurality of parallel and spacedsecond openings 133 and comprises a plurality of second rectangularstructures 131. The second openings 133 is stripe shaped. The secondopenings 133 correspond to the third openings 143, and the secondrectangular structures 131 correspond to the triangular prism structures141. The first metal layer 120 is exposed through the second openings133.

In step S60, the etching the first metal layer 120 is performed in areactive plasma system.

The physical etching gas and the reactive etching gas are introducedinto the etching system. The physical etching gas is argon gas, and thereactive etching gas is a mixture of chlorine gas and oxygen gas. Thephysical etching gas and the reactive etching gas simultaneously etchthe first metal layer 120.

A plurality of first openings 123 are obtained by etching a part of thefirst metal layer 120 corresponding to the second openings 133. Inaddition, some metal particles or powders can be produced and fall offfrom the first metal layer 120 during the etching process. If there isno reactive etching gas, the metal particles or powders will accumulatealong the sidewalls of the first openings 123 to form a thick edge, andthat will also result in a large surface roughness of the sidewalls ofthe first openings 123. A gradient of the etching rate of the firstmetal layer 120 along each direction tends to be stable. Since the metalparticles or powders are deposited on the bottom surfaces of the firstopenings 123, the accumulation of the metal particles or powders on thebottom surfaces of the first openings 123 is equal to a reduction in thevertical etching rate and also equal to an increase in the horizontaletching rate. The excess metal particles or powders deposited on thesidewalls of the first openings 123 can be etched by the reactiveetching gas and the physical etching gas. The first rectangularstructures 121 have a regular structure and a small surface roughness.

The volume flow rate of chlorine gas can be in a range of 1 sccm to 240sccm. Furthermore, the volume flow rate of chlorine gas can be in arange of 1 sccm to 100 sccm. In one exemplary embodiment, the volumeflow rate of chlorine gas is 5 sccm. The volume flow rate of oxygen gascan be in a range of 1 sccm to 260 sccm. Furthermore, the volume flowrate of oxygen gas can be in a range of 1 sccm to 100 sccm. In oneexemplary embodiment, the volume flow rate of oxygen gas is 10 sccm. Thevolume flow rate of argon gas can be in a range of 50 sccm to 500 sccm.In one exemplary embodiment, the volume flow rate of argon gas is 78sccm. The pressure of the system can be in a range of 8 Pa to 110 Pa. Inone exemplary embodiment, the pressure of the system is 16 Pa. The powerof the system can be in a range of 20 watts to 300 watts. In oneexemplary embodiment, the power of the system is 121 watts. The etchingtime can be in a range of 5 minutes to 50 minutes. Furthermore, theetching time can be in a range of 8 minutes to 13 minutes. In oneexemplary embodiment, the etching time is 11 minutes.

The shape of the first openings 123 is regular rectangle after the stepS60 being completed. The width of the first openings 123 is in a rangeof 10 nanometers to 350 nanometers. The width of the first openings 123can be controlled by adjusting the etching time. The thickness of thefirst rectangular structures 121 can be controlled by adjusting theetching time. In one exemplary embodiment, the width of the firstopenings 123 is 150 nanometers.

In step S70, the residual photoresist remains in the structure obtainedby step S60. The pine shaped metal nano-scaled grating 10 is obtained byremoving the residual photoresist. The residual photoresist can beresolved by dissolving agent. The dissolving agent can betetrahydrofuran (THF), acetone, butanone, cyclohexane, n-hexane,methanol, absolute ethanol, or non-toxic or low toxicity ofenvironmentally friendly solvents. In one exemplary embodiment, theresidual photoresist is removed by ultrasonic cleaning in acetonesolution. FIG. 7 and FIG. 8 are SEM images of the pine shaped metalnano-scaled grating.

Referring to FIG. 9, an embodiment of a method of making the pine shapedmetal nano-scaled grating 20 comprises:

-   -   S10A, providing a substrate 200;    -   S20A, forming a first metal layer 220 on the substrate 200,        forming an isolation layer 230 on the first metal layer 220, and        locating a second metal layer 240 on the isolation layer 230;    -   S30A, placing a first mask layer 251 on the second metal layer        240, wherein the first mask layer 251 covers partial surface of        the second metal layer 240, and other surface is exposed;    -   S40A, etching the second metal layer 240 to obtain a plurality        of triangular prism structures 241;    -   S50A, etching the isolation layer 230 to obtain a plurality of        second rectangular structures 231;    -   S60A, etching the first metal layer 220 to obtain a plurality of        first rectangular structures 221; and    -   S70A, depositing a third metal layer 261 on the triangular prism        structures 241 to obtain a three-dimensional nanostructures 210.

The method of making the pine shaped metal nano-scaled grating 20 issimilar to the method of making the pine shaped metal nano-scaledgrating 10 except that the third metal layer 261 is deposited on thetriangular prism structures 241 without removing the first mask layer251. The thickness of the third metal layer 261 is greater than 30nanometers. In one exemplary embodiment, the thickness of the thirdmetal layer 261 is 50 nanometers.

On the one hand, the method of depositing the third metal layer 261 onthe triangular prism structures can adjust the charge distribution inthe preparation process, which is beneficial to the processing. On theother hand, the mask layer don't need to be removed, so procedures ofthe method are simple. The pine shaped metal nano-scaled gratingprepared by the above method can make the diffraction precision reachseveral hundred nanometers.

Referring to FIG. 10, an embodiment of a pine shaped metal nano-scaledgrating 30 comprises a substrate 300 and a plurality ofthree-dimensional nanostructures 310. The substrate 300 defines a firstsurface 3002 and a second surface 3004 corresponding to the firstsurface 3002. The plurality of three-dimensional nanostructures 310 arelocated on both the first surface 3002 and the second surface 3004. Thethree-dimensional nanostructures 310 are pine shaped structures. Thethree-dimensional nanostructures 310 comprises a first rectangularstructure 321, a second rectangular structure 331, and a triangularprism structure 341. The first rectangular structure 321 is located onthe substrate 300. The second rectangular structure 331 is located onthe first rectangular structure 321. The triangular prism structure 341is located on the second rectangular structure 331. The width of thebottom surface of the triangular prism structure 341 is equal to thewidth of the top surface of the second rectangular structure 331 andlarger than the width of the top surface of the first rectangularstructure 321.

The structure of the pine shaped metal nano-scaled grating 30 is similarto the structure of the pine shaped metal nano-scaled grating 10 exceptthat the plurality of pine shape nanostructures 310 are located on boththe first surface 3002 and the second surface 3004.

Referring to FIG. 11, an embodiment of a pine shaped metal nano-scaledgrating 40 comprises a substrate 400 and a plurality ofthree-dimensional nanostructures 410. The plurality of three-dimensionalnanostructures 410 are located on at least one surface of the substrate400. The three-dimensional nanostructures 410 is pine shape structures.The three-dimensional nanostructures 410 comprises a rectangularstructure 421 and a triangular prism structure 441. The rectangularstructure 421 is located on the substrate 400. The triangular prismstructure 441 is located on the rectangular structure 421. The width ofthe bottom surface of the triangular prism structure 441 is greater thanthe width of the top surface of the rectangular structure 421.

Referring to FIG. 12, an embodiment of a method of making the pineshaped metal nano-scaled grating 40 comprises:

-   -   S10B, providing a substrate 400;    -   S20B, forming a first metal layer 420 on the substrate 400, and        locating a second metal layer 440 on the first metal layer 420;    -   S30B, placing a first mask layer 451 on the second metal layer        440, wherein the first mask layer 251 covers partial surface of        the second metal layer 440, and other surface is exposed;    -   S40B, etching the second metal layer 440 to obtain a plurality        of parallel and spaced triangular prism structures 441;    -   S50B, etching the first metal layer 420 to obtain a plurality of        parallel and spaced rectangular structures 421; and    -   S60B, removing the first mask layer 451 to obtain the pine        shaped metal nano-scaled grating 40.

The structure of the pine shaped metal nano-scaled grating 40 is similarto the structure of the pine shaped metal nano-scaled grating 10 exceptthat the pine shape structures consist of the rectangular structures 421and the triangular prism structures 441. The material of the rectangularstructures 421 and the triangular prism structures 441 is metalmaterial. The material of the triangular prism structures 441 isdifferent from the material of the rectangular structures 421.

The triangular prism structure of the pine shaped metal nano-scaledgrating is equivalent to the T-gate. The preparation of T-gate by theabove method is also within the scope of the disclosure.

The pine shaped metal nano-scaled grating of the disclosure has manyapplications. The pine shaped metal nano-scaled grating can realizeresonance of light at different wavelengths, and the third openingsbetween adjacent triangular prism structures can achieve narrowbandresonance. The half width of the narrowband resonance is in a range of0.1 nanometers to 3 nanometers. The wavelength of the formant is in arange from near ultraviolet band to mid-infrared band. The disclosurecan realize the manual operation of light. The light intensity and lightconduction at nanometer scale can be controlled by using the surfaceplasmon resonance of the pine metal nanometer grating. The firstopenings between the two adjacent first rectangular structures canachieve broadband absorption. The first openings can absorb energy andradiate energy in other forms. For example, the first openings canabsorb solar energy, and the solar energy is converted into the energyrequired for chemical reactions, so the first openings can play aphotocatalytic role. The pine shaped metal nano-scaled gratings have agood effect in validating the theoretical model of Fano resonance.

Compared to the prior art, the pine shaped metal nano-scaled grating ofthe disclosure has many advantages. Firstly, the pine shaped metalnano-scaled grating is composed of at least two parts, and differentparts can achieve different effects. Each part constitutes a resonantcavity with a different width. Each resonant cavity can absorb photonsnear the corresponding resonant waves. The structure of the pine shapedmetal nano-scaled grating can effectively extend the range of resonantwaves. The triangular prism structures can achieve narrowband resonanceabsorption, and the rectangular structures can achieve broadbandabsorption. Secondly, the third metal layer is deposited on the surfaceof the hybrid structure of the photoresist and second metal layer, andthe above structure can adjust the charge distribution of the metallayer. Thirdly, the pine shaped metal nano-scaled grating can be made bythe reactive ion etching method. The method can achieve vertical andlateral anisotropic etching. The method can also achieve anisotropicetching in vertical direction to obtain the nanostructures. Fourthly,the nanostructure and the method of making the nanostructure have a wideapplication field. The pine shaped metal nano-scaled gratings haveexcellent optical properties in the near and far fields. The gratingdirection of the pine shaped metal nano-scaled grating can be changed.

The embodiments shown and described above are only examples. Even thoughnumerous characteristics and advantages of the present technology havebeen set forth in the foregoing description, together with details ofthe structure and function of the present disclosure, the disclosure isillustrative only, and changes may be made in the detail, including inmatters of shape, size, and arrangement of the parts within theprinciples of the present disclosure up to, and including, the fullextent established by the broad general meaning of the terms used in theclaims.

Depending on the embodiment, certain of the steps of methods describedmay be removed, others may be added, and the sequence of steps may bealtered. The description and the claims drawn to a method may comprisesome indication in reference to certain steps. However, the indicationused is only to be viewed for identification purposes and not as asuggestion as to an order for the steps.

What is claimed is:
 1. A pine shaped metal nano-scaled grating, thegrating comprising a substrate and a plurality of three-dimensionalnanostructures located on the substrate, wherein each three-dimensionalnanostructure comprises a first rectangular structure, a secondrectangular structure, and a triangular prism structure; the firstrectangular structure is located on the substrate, the secondrectangular structure is located on the first rectangular structure, thetriangular prism structure is located on the second rectangularstructure, a first width of a bottom surface of the triangular prismstructure is equal to a second width of a first top surface of thesecond rectangular structure and greater than a third width of a secondtop surface of the first rectangular structure, and the firstrectangular structure comprises a first metal and the triangular prismstructure comprises a second metal.
 2. The grating as claimed in claim1, wherein the plurality of three-dimensional nanostructures are stripraised structures, and the plurality of three-dimensional nanostructuresare arranged side by side and extend along a straight line, a fold line,or a curve line.
 3. The grating as claimed in claim 1, wherein thebottom surface of the triangular prism structure is completelycoincident with the first top surface of the second rectangularstructure.
 4. The grating as claimed in claim 1, wherein two adjacentthree-dimensional nanostructures are substantially parallel with eachother, and a distance between the two adjacent three-dimensionalnanostructures is in a range of 40 nanometers to 450 nanometers.
 5. Thegrating as claimed in claim 1, wherein the first metal is selected fromthe group consisting of gold, silver, copper, and aluminum; and thesecond metal is selected from the group consisting of gold, silver,copper, and aluminum.
 6. The grating as claimed in claim 1, wherein thesecond rectangular structure is selected from the group consisting ofchromium, thallium pentoxide, titanium dioxide, silicon, and silica. 7.The grating as claimed in claim 1, wherein a first thickness of thefirst rectangular structure is in a range of 20 nanometers to 500nanometers, a second thickness of the second rectangular structure is ina range of 5 nanometers to 100 nanometers, and a third thickness of thetriangular prism structure is in a range of 40 nanometers to 800nanometers.
 8. The grating as claimed in claim 1, further comprises ametal layer located on the triangular prism structure.
 9. A pine shapedmetal nano-scaled grating, the grating comprising a substrate and aplurality of three-dimensional nanostructures located on at least onesurface of the substrate, wherein each three-dimensional nanostructurecomprises a rectangular structure and a triangular prism structure, therectangular structure is placed directly on the substrate, thetriangular prism structure is located on the rectangular structure, afirst width of a bottom surface of the triangular prism structure isgreater than a second width of a top surface of the rectangularstructure, and the rectangular structure comprises a first metal and thetriangular prism structure comprises a second metal, and the first metalis different from the second metal.
 10. The grating as claimed in claim9, wherein the first metal is selected from the group consisting ofgold, silver, copper, and aluminum; and the second metal is selectedfrom the group consisting of gold, silver, copper, and aluminum.